At midday, the 12Z GFS forecasts a whopping -4 value for the East Pacific oscillation (EPO) during the 11-15-day period. Other models are averaging -2 at that timeframe, about half the strength (although still impressive). The strong (-4) index supports arctic air involvement and on day-15, 12Z GFS indicates zero for morning low temperatures from Colorado to South Dakota. Is the forecast overstated?

An intense negative North Atlantic oscillation (-NAO) weather pattern continues into early next week. Reasonable is the projection by ECM of another intense -NAO inspired upper trough into the Northeast late this weekend. The upper trough triggers more chilly weather although not quite as cold as today plus a major snowstorm over Maine.

Climate forecasts are maintaining wet Brazil forecasts for early-to-middle summer 2025-26. The operational extended range forecasts agree as ECMWF projects wet conditions in Central to East Brazil compensated for by dry and hot weather in Northeast Argentina/Southeast Brazil.

During the past 60 days, the NOAA AI Eagle has performed well forecasting the weather pattern (500 MB anomalies) across the northern hemisphere during the 6-10-day/11-15-day medium range forecast.